1. Field of the Invention
The apparatus and methods consistent with the present invention relates to mobile computers for use in wireless local area networks, and more particularly to the security network architecture, configuration software and communications protocols needed to support the biometric identification of an authorized user of a mobile unit to be operated in such networks, and from one secure network to another secure network.
2. Glossary of Terms
Access Agent: A logical component that provides support for different access protocols and streams—Frame Relay, HDLC (High Data link Control) CBO (Continuous bit Operations, ATM (Asynchronous Transfer Mode), or TCP/IP.
Call (noun): Point-to point multimedia communication between two IP network endpoints. The call begins with the call setup procedure and ends with the call termination procedure. The call consists of the collection of reliable and unreliable channels between, all the channels terminate at the Gateway where they are converted to the appropriate representation for the PSTN end system.
Caller: The entity initiating a call.
Called: The destination of a call
Dynamic Address Mapping Service: A service which provides a lookup function between text based strings and IP addresses and/or phone numbers, where the result of the lookup can change relatively quickly over time.
Endpoint: An H.323 Terminal or Gateway. An endpoint can call and be called. It generates and/or terminates information streams.
Gatekeeper: The Gatekeeper (GK) is an H.323 entity that provides address translation and controls access to the network for H.323 Terminals and Gateways. The Gatekeeper may also provide other services to the H.323 Terminal and gateways, such as bandwidth management and locating Gateways.
Gateway: An H.323 Gateway (GW) is an endpoint which provides for real-time, two way communications between H.323 Terminal on a IP network and: other ITU terminals; phones on the PSTN; other terminals on other networks.
H.323 Entity: Any H.323 component, including H.323 Terminals, Gateways, Gatekeepers.
IMTC: (International Multimedia Teleconferencing Consortium) An organization whose mission is to bring together all organizations involved in the development of interactive, multimedia teleconferencing products and services to help create and promote the adoption of industry-wide interoperability standards. The VoIP forum is part of the IMTC.
Information Stream: A flow of information of a specific media type (e.g. audio) from a single source to one or more destinations.
Internet address: The network layer address of an H.323 endpoint, Gatekeeper, or DNS server.
Internet: An inter-network of networks interconnected by bridges or routers. LANS described in H.323 may be considered parts of such internetworks.
IP network: A network that uses IP as the network layer protocol. This includes networks such as Internet, Intranets, LANs etc.
RAS Channels: Unreliable channels used to convey the registration, admissions, bandwidth change, and status messages (following H.225.0) between H.323 entities.
Reliable Channel: A transport connection used for reliable transmission of an information stream from its source to one or more destinations.
Reliable Transmission: Transmission of messages from a sender to a receiver using connection-mode data transmission. The transmission service guarantees sequenced, error-free, flow-controlled transmission of messages to the receiver for the duration of the transport connection.
Transport Connection: An association established by a transport layer between two H.323 entities for the transport of data. In the context of H.323, a transport connection provides reliable transmission of information.
VoIP: Voice over Internet Protocol. The VoIP Forum is developer of specification of such protocol.
Zone: A zone, as defined in H.323, is a collection of all terminals, Gateways (GW), and Multipoint Control Units (MCU) managed by a single Gatekeeper (GK).
3. Background of the Invention
a. Communications Networks
A typical data communications network system comprises at least one server and two or more clients interconnected through a network link. The International Standards Organization (ISO) has published specifications for their Open Systems Interconnection (OSI) reference model for layered data communications, which has become a standard framework for describing network communications systems. The ISO reference model is divided into seven layers, each defining a set of services and related protocols for handling messages at that layer. The ISO's reference model defines the following seven layers; (1) physical; (2) data link; (3) network; (4) transport; (5) session; (6) presentation; and (7) application. Since the concepts and teachings of the present invention generally fall within the transport through application layers; a detailed discussion of the operations taking place at the lowermost (e.g., physical, data link, and network) layers was not necessary for purposes of describing the present invention, as the operations at these levels are known to those skilled in the art and are transparent to the operations of the present invention.
The physical layer comprises the actual physical devices and medium used to transmit information. The data link layer frames data packets and controls physical layer data flow, insuring delivery of data regardless of the actual physical medium. The network layer addresses and routes data packets. It creates and maintains a route in the network between a source node and a destination node. The transport layer creates a transport pipeline between nodes and manages the network layer connections. The session layer typically provides remote procedure call (RPC) support, maintains the integrity of the connection between nodes, and controls data exchange. The presentation layer encodes and decodes data and provides transparency between nodes. Finally, the application layer provides the interface to end-user processes and provides standardized services to applications.
b. Wireless LANs
Wireless local area networks use infrared or radio frequency communications channels to communicate between portable or mobile computer terminals and stationary access points or base stations. These access points are in turn connected by a wired (or possibly wireless) communication channel to a network infrastructure which connects groups of access points together to form a local area network, including, optionally, one or more servers or host computer systems.
Wireless and radio frequency (RF) protocols are known which support the logical interconnection of portable roaming terminals having a variety of types of communication capabilities to host computers. The logical interconnections are based upon an infrastructure in which at least some of the remote terminals are capable of communicating with at least two of the access points when located within a predetermined range therefrom, each terminal unit being normally associated with and in communication with a single one of such access points. Based on the overall spatial layout, response time, and loading requirements of the network, different networking schemes and communication protocols have been designed so as to most efficiently regulate the communications between a given terminal and the network through the selected access point. One such protocol is described in U.S. Pat. Nos. 5,029,183; 5,142,550; 5,280,498; and 5,668,803, each assigned to Symbol Technologies, Inc. and incorporated herein by reference.
Another such protocol is described in U.S. Pat. No. 5,673,031. Still another protocol is set forth in the ISO/IEC 8802-11, or ANSI/IEEE Std 802.11 entitled “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications” (1999 edition) available from the IEEE Standards Department, Piscataway, N.J. (hereinafter the “IEEE 802.11 Standard”).
The IEEE Project 802 is concerned with network architecture for local area networks. The IEEE 802.11 Standard is directed to wireless local area networks, and in particular specifies the MAC or the data link layer and the PHY or physical link layer.
In Europe, the European Telecommunications Standards Institute (ETSI) has been working on HIPERLAN (European High PERformance LAN), the next generation of high speed wireless systems. The frequency spectrum for HIPERLAN in the 5 GHz and 17 GHz bands has been allocated by the European Conference of Postal and Telecommunications Administrations (CEPT), with a data rate of over 20 Mbit/sec.
c. Modulation Techniques
The current implementations of commercial wireless LAN networks utilize a radio operating in the 2.4 to 2.4835 GHz spread spectrum band which is the industrial, scientific, and medical (ISM) band allocated for unlicensed use by the FCC. The current systems utilize one of two basic types of spread spectrum modulation: direct-sequence and frequency-hopping, or a technique known as complementary code keying (CCK).
d. Roaming
The term “roaming” relates to mobile units associating with different access points. Each mobile unit analyzes received signals from access points to identify and associate with an eligible access point. Analogous to cells in a cellular telephone network, the region around a given access point may also be referred to as a “cell.” Roaming between cells provides great flexibility and is particularly advantageous in locations that are difficult to wire, for simple relocation of work stations, and for portable work stations.
Although the IEEE 802.11 Standard provides the basic packet types which enable roaming, it does not actually set the roaming algorithm. According to the standard, the mobile unit determines the access point with which it will associate and the access point must accept the mobile unit unless the access point is defective or certain alarm conditions exist, such as memory full. There is, however, no suggestion of how, or by what criteria, other than those mentioned above, the mobile unit might select an appropriate access point, or an optimum access point.
In order for a mobile unit to associate with an access unit the mobile unit follows an association protocol. The mobile unit firstly sends out a probe packet having no destination address which is accordingly accepted by all access units within range. The probe packet contains an identifying address for the mobile unit has sent it. The access unit then transmits a probe response packet which includes information such as the access unit address, the hopping pattern, the present channel, time left in the present channel and other timing information. The mobile unit then decides whether or not to associate with a given access unit, based on for example the strength of the signal of the access unit and any information the access unit may have issued indicating how many mobile units are already associated with it. If the mobile unit decides to associate, it sends an associate message or packet and the access unit decides whether to accept the association request and issues an association response after the request is accepted.
In addition the access unit transmits a “beacon” at predetermined intervals containing, in addition to other information, timing information similar to that contained in probe response packet.
The mobile units can operate in two power management modes, either continuously awake mode (CAM) or power save polling (PSP) mode. In the former mode, CAM, the mobile unit remains in substantially continuous communication with an access unit so as to receive and transmit all information intended for the mobile unit practically instantaneously. Of course that mode of operation requires a high level of power consumption which is not always desirable for a portable mobile unit which is relying on internal power such as batteries. In the alternative PSP mode, the mobile unit sends out a polling signal at predetermined intervals of time to enquire whether an associated access unit has stored any messages for that mobile unit in a suitable buffer. Similarly the mobile unit can store any message to be transmitted in a buffer and transmit all of the messages so stored at predetermined intervals. Such a mode of operation clearly allows decreased power consumption. Under the IEEE 802.11 protocol the beacon signal contains information about which PSP stations have data waiting.
e. Coordination Functions
In the IEEE 802.11 network architecture, the management of stations within a region in which the station can communicate with each other is performed by software known generically as a Coordination Function (CF). A group of mobile units that can communicate with one another is known as a basic service set or BSS. In order to ensure that communications are coordinated, the CF determines when a station operating within a BSS is permitted to transmit and may be able to receive protocol data units (PDUs) via the wireless medium. The BSS is formally defined as the set of stations controlled by a single Coordination Function. There are two types of coordination functions—the Distributed Coordination Function (DCF), and the Point Coordination Function (PCF). The use of DCF is mandatory, while PCF is optional under the IEEE 802.11-1999 standard.
A larger group of network units, called the extended service set or ESS is defined as a set of one or more interconnected Basic Service Sets and integrated LANS which appear as a single BSS to the logical link control (LLC) layer at any station associated with one of those BSSs.
The key concept is that the ESS network appears the same to an LLC layer as an independent BSS network. Stations anywhere within an ESS may communicate with each other and mobile stations may move from one BSS to another (within the same ESS) transparently to LLC. Mobile units communicate with an AP, and the AP forwards to traffic among themselves to the destination BSS, thus facilitating the roaming of mobile units from one BSS to another.
One (or more) independent BSS or ESS networks may be physically present in the same space as one or more ESS networks. For example, an ad hoc network may be operated in the region of an ESS network; or physically overlapping independent IEEE 802.11 networks may be set up by different adjacently located organizations, each with their own ESS identification code.
f. Security
IEEE 802.11 specifies an optional privacy algorithm, WEP that is designed to satisfy the goal of wired LAN “equivalent” privacy. The algorithm is not designed for ultimate security but rather to be “at least as secure as a wire.” IEEE 802.11 uses the WEP mechanism to perform the actual encryption of messages. Privacy may only be invoked for data frames and some Authentication Management frames. All stations initially start “in the clear” in order to set up the authentication.